Flexible joint



April 13 1926.

H. P. MACDONALD FLEXIBLE JO INT Filed August 6, 1919 2 Sheets-Sheet 2 ice Patented Apr. 13, 1926.

UNITED STATES PATENT oFFicE.

HARRY P. MACDONALD, OF MONTCLAIR, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGN-MENTS, T0 SPICER MANUFACTURING CORPORATION, OF SOUTH PLAINFIELD,`N`EWJERSEY, A CORPORATION OF VIRGINIA.

FLEXIBLE JOINT.

Application led August 6, 1919. Serial No. 315,613.

To all whom t 'may concern:

Be it known that I, HARRY P. MACDONALD, a citizen of the United States,residing at Montclair, in the county of Essex and State of New Jersey,lhave invented certain new and useful Improvements in Flexible Joints,of which the following is a specification.

This invention relates to tiexible joints, such, for example, as areused in the transmission of power, the joint being p articularly usefulin automobile drives.

The invention relates in general to that type of flexible joint in whichthe torque of the drive shaft is transmitted to the driven shaft throughthe medium of one or more flexible discs, connected alternately `t0 thefeet of the-spiders on the respective shafts, by means of bolts.

It has been attempted to distribute the strain on'the discs over as widean area as possible for the purpose of relieving those portions of thediscs immediately adjacent the bolt hole openings from a portion of thestresses, by providing the feet of the spiders and Ialso the washersspacing the discs with roughened surfaces, .-such, for example, asradial fluting or a plurality of concentric eorrugations, or. aplurality of ribs extending transversely of the line of thrust. Suchconstructions, however, have largely failed of their object by reason ofthe fact that the discs are composed of pliable material usuallycontaining an amount of rubber sufficient to make the discs racticallyflow under pressure, the result being that when pressure is brought uponthe discs by tightening the spider bolts, the Greater part, if not theentire area of the dises under the washers and the spider feet vissubjected to a pressure which tends to force the material from under thewashers and spider feet; and when to thisvtendency is added the workingstrain on the discs, the fabric very readily flows and begins to slip.When this occurs failure of the coupling rapidly follows.

It is one of the primary objects of my invention to overcome theforegoing difficulty and to provide a coupling` which not only has agreatly extended period of life, but which is also relatively muchstronger and will stand up under greater loads.

The foregoing together with such other objects as may hereinafterappear, I obtain by means of a construction, the referred embodiments ofwhich I have il ustrated in the accompanying drawings, wherein,

Figure 1 is a cross section through a single bolt per spider footflexible joint embodying my improvement; Figure 2 is an elevation ofFigure 1; Figure 3 is a fragmentary side elevation of a spider foot ofthe two bolt type; Figure l1 is a cross section through a two bolt perfootspider; Figure 5 is an end elevation of' Figure 4, artially brokenaway; Figure'G is an 'enarged section, more clearly illustrating certainof the details of my improvement; Figure 7 is a plan view of the singlebolt ring washer; and Figure 8 is a plan view of the double bolt ringwasher.

Referring noiv to Figure 1, the, shaft 7 may be considered as thedriving shaft, and rthe shaft 8, as the driven sha-ft, of some form ofpower transmission means. Each shaft is provided with a spider 9 havinga plurality of feet 10, preferably three in number. Between the spidersare the iexible discs 11, preferably composed of plates of fabric andrubber as is customary in this art. At equally spaced intervals, thediscs are alternately connected to the feet of the respective spiders bymeans of bolts 12.

In the single bolt per spider foot construction shoivn in Figures 1 andQ, the feet are preferably circular 'at their ex'- tremitics, and ontheir outer faces, at the periphery, they are provided with an0utstanding annular rim or bead 13, projecting well bevond the face ofthe spider feet. Between adjacent discs I provide spacing members orrings 14 in the nature of washers, said members having a ring or roundedrim 15 at the periphery, preferably considerably thicker than theweb-like inner portion of the washers. The outside washers 16, comingunder the heads of the bolts 12, are also provided with rings orthickened rims 15, but for these washers the rim need project fromoneface only. A plurality of ears 17 are struck up from the washers 16 andare adapted to engage the head of the bolt and prevent the bolt fromturning with reference to the nuts.- The nuts 18 for the bolts are heldagainst loosening by means of lock washers 19.

It will be noted that the construction is such that when the bolts 18are ti htened, the bead-like marginal rings or ri ges 12, 15 of thedished connecting or gripping means-the spider feet 10 and the Washers14, 16-are pressed and sunk into the disc material around thecorresponding connective areas of the disc, beneath these grippingmeans; and there is practically little, if any, pressure tending toforce or squeeze the material out from under the gri ping means. On thecontrary, the action o the rims or ridges 12, 15 is to effectuallyconfine the material of the connective areas a ainst any tendency tosqueeze out under sui pressure as the connecting means may exert onthese areas. This confinement results both from the greater intensity ofpressure on the zones of engagement with the rims 12, 15 and from thefact that these rims are sunk in the disc faces below the connectiveareas. As shown, the material within these areas is left substantiallundistorted, as compared with the zones ofy rim pressure, since theplain, flat surfaces within the` rims 12, 15 can at most only exert arelatively light and substantially uniform lateral pressure on theseareas; and driving is effected through each connective area as a whole.As shown in Fig. 1, the margins or lateral ridges 12, 15 of the dishedconnective means 10, 14, 16, at opposite sides of each fiexible disc 11are engaged with and sunk into the disc along coincident zones.

The confinement of the connective disc areas and the driving througheach of them as a whole (as described above) are contrary to thfi`ect ofplain washers, radially fluted washers and concentrically corrugatedwashers, in all of which, although the pressure may not be equallydistributed, there 1s an effective pressure from the bolt outward whichtends to force the material from the bolt hole outward from beneath thefeet and washers.

The effects are especially different in the case of laminated discs ofrubberized fabric, since plain, radially fluted, and concentricallycorrugated washers all tend to depress the fabric layers of such a discuniformly below the boundary of its connective area, rather than to gripthese la ers themselves effectively along such boun ary withoutdisplacement within it-as do dished connective means such as I havedescribed.

I have found as a result of experiment that in this construction theload may be increased almost 50% before slippage takes place and theultimate load at which the discs will fail is increased bv approximately30%. I attribute this to the fact that the feet and washers, while theyhave a firm grip on the discs and thus distribute the stresses,nevertheless do not tend to squeeze or force out the material.

In addition less pressure is required on the bolt to secure a firm gripon the discs than with. the standard construction heretofore employed,and there is less tendency for the bolt to work loose, even in theabsence of the ears 17 because of the greater elasticity obtained due tothe pressure of the rims or rings coming on a relatively small area ofthe disc.

In the construction shown in Figures 3 to 5 inclusive, the feet 10 ofthe spider are providedwith two radially disposed bolt holes 20, and thebead 13', in this case, instead of being circular, follows the shape ofthe foot, as illustrated in Figure 5. The washers 14 are correspondinglyelongated and provided with two bolt holes, the rim.

15 corresponding in outline to the bead 13 of the feet of the spiders.

I claim:-

1. .In a torque-transmitting flexible coupling, the combination withflexible discs of' connecting means including lateral clamps, bolt-likemembers through the discs securing the clamps together,"and washers onsaid members between discs marginally beaded and sunk therein, butleaving the discs substantially uudistorted within the zones of suchengagement, the margin of' the washer being well removed from the holetherein.

2. A connective device for a flexible torque-transmitting disccomprising a washer laterally ridged at its margin, but otherwisesubstantially plain, the margin of thc Washer being well removed fromthe hole therein.

3. A connective device for a flexible torque-transmitting disccomprising a washer marginally beaded toward both faces, butsubstantially plain within its beaded mar- 1n. g In testimony whereof Ihave hereunto signed my name.

HARRY P. MACDONALD.

